Air conditioning systems require energy for raising and lowering air temperature and which can be assisted by the storage of "solar insolation" heated liquid and/or conversely by the storage of "terrestrial re-radiation" cooled liquid, and also assisted by absorption from or into the surrounding ambient air. The utilization of said forms of energy storage has been practiced independently and aggregatively, but not cooperatively as will be disclosed herein and combined in a system characterized by a stratified thermal mass that separates the several heat transferring circuits that must operate within different temperature ranges, respectively.
The prior art operation of water source heat pumps has been restrictive in various respects. For instance, diversity which permits a reduction in building co-incident load demands has been available only on the heating cycle, while on the cooling cycle there has been no such diversity capability since with the mechanical refrigeration equipment physically in each pre-selected temperature control zone there is no conventional means to re-distribute the excess cooling capacity of any unit at any given time to other heat pump units similarily operating on a cooling cycle. On the contrary, the present invention provides diversity on cooling, as well as on heating, through the introduction of cold thermal storage applied as hereinafter described. Further, the prior art systems of the type under consideration have not minimized thermal differential, or Delta-T, in the cooperative relationship of solar collectors and thermal mass heat storage, as it is accomplished by means of the stratified mass hereinafter disclosed and tapped at optimum temperature ranges as related to purpose. Still further, the prior art has not taken full advantage of the availability of temperature differences at separated zones being air conditioned, whereas the present invention provides each heat pump with either hot mass or cold mass assistance, thereby reducing unit capacity requirements and providing for full peak operation of independent units, as circumstances require.
The collection of solar heat energy is normally within a range of nominally 100.degree. to 180.degree. F or higher, while the heat pump is properly operative from a water source within a range of 55.degree. to 90.degree. F; and these high and moderate ranges require commensurately proportioned thermal masses for effective utilization of stored heat energy. To these ends I have provided a stratified thermal mass in the form of a compartmented liquid storage tank wherein the solar heat is stored at high temperatures, wherein the heat pump water source withdraws heat at moderate temperatures, and wherein residual heat at low temperatures is utilized for auxiliary purposes such as to preheat a domestic hot water supply. It is an object, therefore, to cooperatively relate and combine the solar energy assistance with the operational requirements of a water source heat pump and to utilize residual heat to the fullest extent. Additionally, it is an object to maintain a cold liquid storage which becomes necessary, at times, to provide supplementary cooling capacity for the heat pump when in the cooling mode, and to this end I have provided cooling means, both by mechanical and by terrestrial re-radiation, and cooperatively associated with the heat pump to be used directly in the cooling of recirculated useful air for which the system is designed to condition.
It is assistance for one or more liquid or water source heat pumps with which the present invention is concerned, a comprehensive concept which involves the conservation of energy, both by collection of available solar insolation and by use of terrestrial re-radiation, and assisted by heat absorption to or from and from within the system under extreme conditions. It is to be observed, particularly, that the more or less predictable collection of solar energy in a thermal mass is variable to say the least, however beneficial that heat may be. It is also to be observed, particularly, that water source heat pumps have a practical operating range, at times below the temperature of said thermal mass storage of solar energy and at times above said thermal mass temperature, at whatever temperature variant said mass might be above or below the range of normal heat pump operation. That is, there will be times when the remaining solar energy stored in the thermal mass is less than said 55 .degree. F minimum, and times when more than said 90.degree. F maximum. To this end, therefore, the thermal mass is stratified in accordance with the present invention in a compartmented storage tank employing thermal convection for circulation of a liquid mass therein between a high heat section, a moderate heat section, and a low heat section. It is an object to maintain as nearly as possible a 55.degree.-90.degree. F heat range within the intermediate section, and to this end it is embraced between the high and low temperature sections for their cooperative effect in transferring heat thereto and therefrom.
Application of heat is coextensive of the three aforementioned heat range sections of the stratified thermal mass, it being an object to provide maximum thermal differential between the inlet and outlet of the solar heat collector. To this end, solar panels or the like are employed and from which the collected heat is applied to the high heat range section, and the heat progressively absorbed into the thermal mass as the liquid transfer media moves toward the low heat range section. With the stratification of high to low temperature within the mass, the thermal differential is increased between the outlet and inlet of the solar panel-collector.
Withdrawal of heat from the intermediate section of the thermal mass storage is by means of a closed loop pumping circuit through a mixing or proportioning valve and through a water to refrigerant heat exchanger, whereby the said water source to the heat exchanger is controlled within the 55.degree.-90.degree. F. water source range as by means of a thermostat control over said valve. In accordance with the invention provision is made for extraordinary conditions, one to apply heat as by the application of external energy and the other to remove heat as by the absorption of heat from the closed loop pumping circuit.
It is an object of this invention to provide an air conditioning system that is applicable to one or a plurality of temperature controlled zones, each conditioned by a water source heat pump associated with hot and cold thermal mass storage, the water source being assisted thereby to remain within the practical operational range of 55.degree.-90.degree. F on demand sensed by thermostat control applying and removing heat energy as required.